Psoriasis is a chronic skin disease which is known to be difficult to treat. Psoriasis is characterized by discrete and confluent, reddish, silvery-scaled maculopapules. These psoriatic lesions occur most often on the elbows, knees, trunk and scalp. Current treatments for psoriasis include the use of agents such an anthralin (dihydroxyanthralin), azarabine, colchicine, fluorouracil, methotrexate, methoxsalen (8-methoxypsoralen), resorcinol, retinoids (for example, retinoic acid), corticosteroids (for example, clobetasol propionate, triamcinolone acetonide and the like), cyclosporin, iodochlorhydroxyquin, salicylic acid, vitamin D, dapsone, somatostatin, sulfur, tars and zinc oxide. Ultra-violet light treatment, alone or in combination with other agents such as psoralen (i.e., PUVA therapy), is also used to treat psoriasis.
There are reports that the activity of the renin-angiotensin-aldosterone system is enhanced in patients with psoriasis (Ena, et al., Acta Cardiologica XL 199 (1985); Ryder, et al., Clin. Chem. Acta 153 143 (1985)). However, there is no established cause and effect relationship between the renin-angiotensin-aldosterone system and psoriasis.
The enzyme renin cleaves the circulating peptide angiotensinogen to produce angiotensin I (AI). Angiotensin converting enzyme (ACE) then cleaves angiotensin I to produce angiotensin II. Angiotensin II causes vasoconstriction and stimulation of the adrenal cortex to release aldosterone, a hormone which causes sodium retention. Sodium retention causes blood volume to increase, which leads to hypertension.
Angiotensin II antagonists have been disclosed as agents for the treatment of hypertension, congestive heart failure, renal failure and elevated intraocular pressure.